The conventional technology either uses lateral movement of manually engageable claw arms, such as manufactured by Hy-Tech (also known as Hydra-Tech) or uses rotatable swivel arm claws, such as manufactured by Dynamic International Vulcan Equipment Co, Inc., and Jerr-Dan Corporation.
Other prior art includes U.S. Pat. No. 4,564,207 of Russ, dated Jan. 14, 1986, which describes a wheel lift device with rotatable L-shaped swivel arm claws, such as manufactured by Dynamic International, Inc. of Norfolk, Va. Furthermore, U.S. Pat. No. 5,326,216 also of Russ describes a swivelable wheel scoop, as does U.S. Pat. No. 5,722,810 of Young, et al, assigned to Jerr-Dan Corp.
In Russ '207, Russ '626, and Young et al '810, the cross beam does not move laterally perpendicular to the axis of the support beam extending out from the back of the tow truck. Moreover, the swivel arm claws are not tapered to be adjustable for various wheel base widths or for various sized vehicle tires. While the swivel arm claws are pivotable, the piston guiding the swivel arm claw pivoting moves parallel to the axis of the transverse cross bar.
Moreover, U.S. Pat. No. 4,473,334 of Brown describes rotatable wheel lift claws, similar to those of Dynamic or Century Wreckers.
U.S. Pat. No. 5,692,871 of Nespor, dated Dec. 2, 1997, and assigned to Chevron, Inc. describes a chain movable rotatable swivel arm scoop, wherein the tires of the vehicle are held adjacent to the proximal portion of the swivel arm scoop adjacent to the cross beam. In Nespor '871 the chain moves about a sprocket, and the swivel arm scoops do not move laterally outward and inward parallel to the axis of the cross beam. Nespor '871 does not provide an auxiliary brace to distribute the heavy weight of a towed vehicle against the pivotable swivel arm scoop.
U.S. Pat. No. 4,929,142 of Nespor describes a tilting vehicle carrier, U.S. Pat. No. 5,061,147 also of Nespor describes a wheel lift brace, U.S. Pat. No. 4,927,315 also of Nespor describes a boom retracting device for a wheel lift and U.S. Pat. No. 5,628,609 also of Nespor shows manually rotatable L-shaped wheel scoops attached to a transverse cross beam.
U.S. Pat. No. 4,836,737 of Holmes describes a wheel lift tow assembly with manually insertable L-shaped wheel scoops, U.S. Pat. No. 4,986,720 also of Holmes describes quick connect wheel cradles with a safety feature to prevent dislodging during towing of a disabled vehicle, and U.S. Pat. No. 4,679,978 also of Holmes, also describes a wheel lift tow assembly with manually insertable L-shaped wheel scoops.
Other Patents include U.S. Pat. No. 4,871,291 of Moore for a wheel lift with manual arm scoops and U.S. Pat. No. 4,904,146 of Lock also for a wheel lift with manual arm scoops.
U.S. Pat. No. 3,620,393 of Bubik describes a tow bar assembly, U.S. Pat. No. 4,637,623 also of Bubik discloses a wheel lift, U.S. Pat. No. 4,795,303 also of Bubik describes a wheel lift which cradles wheels from below, U.S. Pat. No. 4,383,807 also of Bubik discloses a wheel lift sling assembly, U.S. Pat. No. 4,798,509 also of Bubik describes rotatable swivel arm scoops and U.S. Pat. No. 5,354,167 of Callum discloses underlift mechanisms. Design Pat. No. Des. 310,980 describes the exterior design of a towing vehicle body.
Further patents include U.S. Pat. No. 5,133,633 of Grabba for a flat bed tow truck, U.S. Pat. No. 5,672,042 of Bartel, which describes a wheel lift assembly, U.S. Pat. No. 4,239,275 of Horneys for a multi-vehicle tow truck, and U.S. Pat. No. 5,575,606 of Kiefer which describes a wheel lift with apparently manually rotatable scoop arms.
U.S. Pat. No. 4,678,392 of Capers describes a wheel lift with wheel scoops which respond to movement of the wheel upon contact.
U.S. Pat. No. 5,518,260 of Grignon discloses a wheel lift with movable jaws, but wherein the vehicle is movable for a short distance within a garage upon rollers.
U.S. Pat. No. 4,573,857 of Porter describes a wheel lift with lockable wheel support members.
U.S. Pat. No. 4,712,967 discloses a dolly type car carrier and U.S. Pat. No. 4,586,866 of Kvamme, describes a wheel lift with manual wheel supports.
U.S. Pat. No. 4,741,661 of Carey describes manual L-shaped scoop assemblies, U.S. Pat. No. 5,236,214 of Taylor describes improvements to the boom of an underlift assembly, U.S. Pat. No. 4,451,193 of Cannon discloses a boom supported wheel lift carrier, U.S. Pat. No. 5,560,628 of Horn describes a vertically movable towing assembly and U.S. Pat. No. 5,205,700 of Lin describes a hoist mechanism for a vehicle carrier.
Other patents include U.S. Pat. No. 5,350,271 of Weller for a wheel lift with swivel arm scoops which are rotatable by the force of cylinders and levers. In Weller '271 the swivel arm scoops are not laterally movable. Moreover, each swivel arm scoop is L-shaped but with no taper to accommodate various wheel sizes. In addition, in a position of rest the cross beam with the swivel arm scoops thereon sticks out from the end of the tow truck, which is a safety hazard.
U.S. Pat. No. 5,391,044 of Young describes a wheel lift with non-rotatable L-shaped wheel scoops, U.S. Pat. No. 5,352,083 of Roberts describes a wheel lift with non-rotatable L-shaped scoops having swivelable tire engaging portions, U.S. Pat. No. 4,384,817 of Peterson describes a frame mounted vehicle lift assembly and U.S. Pat. No. 4,797,058 of Bilas describes a wheel lift assembly.
Furthermore, U.S. Pat. No. 4,632,629 of Kooima describes a wheel lift with laterally movable but otherwise stationary U-shaped wheel scoop jaws. U.S. Pat. No. 4,557,496 of Sill, also describes a wheel lift with laterally movable but otherwise stationary U-shaped wheel scoop jaws, and U.S. Pat. No. 4,534,579 of Shackleford discloses a wheel lift assembly with pivotable wheel engaging fork members. U.S. Pat. No. 4,473,237 of Lind discloses a wheel lift which includes square shaped members which have to be inserted under the wheels when the vehicle frame is first lifted otherwise.
In addition U.S. Pat. No. 4,034,873 of Haring describes a sling apparatus with manually installable wheel cradle scoops, U.S. Pat. No. 3,667,630 of Scott discloses a vehicle tow assembly with lockable wheel engaging members, U.S. Pat. No. 3,719,294 of Aquilla describes a vehicle tow assembly, U.S. Pat. No. 4,149,643 of Skala describes a truck tow lift which engages the truck frame, U.S. Pat. No. 5,607,279 of Hill describes a flat bed tow truck with a hoist mechanism and U.S. Pat. No. 4,815,915 of Crupi describes an auxiliary tow for a truck which tows a vehicle by engaging its frame.
Moreover, U.S. Patent Nos. 3,434,607 and 3,434,608 of Nelson describe stationary wheel lift assemblies. However the prior art does not describe a wheel lift device having a pair of hydraulically rotatable swivel arm scoops which support the wheels of a disabled vehicle, wherein the swivel arm scoops are also laterally movable parallel to the axis of a cross beam extending transverse to the longitudinal axis of the tow truck itself.
None of the patents cited above have cross bar slider arms that automatically move laterally perpendicular to the axis of the support beam extending out from the back of the truck at the same time that tapered wheel lifting claws are hydraulically activated.